The present invention concerns, in part, an apparatus as defined in the preambles of claims 1and 10, and a method as defined in the preamble of claim 15.
Each of commonly assigned patent references DE 40 39 629 C2 (which has a corresponding PCT reference WO 92/10377) and DE 42 28 414 A1 relate to devices and methods in the field of regulating vehicle dynamics or movements. According to an abstract of DE 40 39 629 C2, it concerns a system for generating signals for adjusting or controlling a vehicle body. To reduce certain movements of the vehicle, speed sensor signals and suspension deflection sensor signals are involved in determining the vehicle speed and the longitudinal and transverse vehicle accelerations. Vehicle movements, which may include xe2x80x9cproperxe2x80x9d swinging, pitching-or-rolling movements and xe2x80x9cproperxe2x80x9d vertical displacements of the front and rear of the vehicle, are involved in compensating or controlling the vehicle suspension systems. Additionally, according to an abstract of DE 42 28 414 A1, a signal processing system detects a first set of signals that represent the movement of the vehicle relative to a fixed reference system, and uses these signals to provide a corresponding set of corrected signals for a travel path of the vehicle. In particular, the sensor signals may represent the transverse velocity and the longitudinal, transverse and vertical accelerations of the vehicle. As discussed in the abstract, the system may be used to control or regulate an active vehicle suspension system, and may correct for certain vehicle movements relative to an inclined path that may be associated with the gravitational acceleration components of the measured signals.
Vehicle brake-by-wire systems, such as, for example, electromechanical brake systems or electro-hydraulic brake systems, may be equipped with wheel braking force control, wheel braking torque control or other anti-lock brake control systems, and may also be provided with a deceleration control system. In a deceleration control system of a brake-by-wire system, there may be no fixed setpoint value for a wheel deceleration that may be associated or correlated with a particular level of brake-pedal travel or brake-pedal force that corresponds with the experience or experiential frame of reference of a driver. Accordingly, a deceleration control system may present certain problems in determining or obtaining an expected or setpoint deceleration value for a particular point on a xe2x80x9cdriverxe2x80x9d or a xe2x80x9cbrake pedal operationxe2x80x9d characteristic curve. It is believed that this is because in such a deceleration control system or xe2x80x9cdeceleration pedalxe2x80x9d braking system, an unpressed brake pedal may correspond to a wheel deceleration of zero (0) and an actuated or depressed brake pedal may correspond to a wheel acceleration that is less than zero (0). In particular, one problem that may occur, for example, is when a driver is driving down a hill. In such a case, the driver may achieve wheel acceleration even while depressing the brake pedal. Any such wheel acceleration, of course, should be less than the wheel acceleration that might result if the driver did not actuate or depress the brake pedal. That is, when driving down a hill, the vehicle may accelerate more if the brake pedal is not actuated or depressed. If the driver increases the force on the brake pedal, this should reduce wheel acceleration to zero (0) and eventually make it negative so that there is wheel deceleration, rather than wheel acceleration.
This braking behavior may be simulated by determining an instantaneous unbraked wheel acceleration and adding it as an offset to a characteristic curve of the xe2x80x9cbrake pedal operationxe2x80x9d for a driver. If the unbraked wheel acceleration offset is not determined during actual braking conditions, however, then the characteristic curve of the xe2x80x9cbrake pedal operationxe2x80x9d may depart (in a possibly dangerous manner or way) from the experience or experiential frame of reference of the driver. For example, when driving off of a car transporter ramp, for example, or down some other incline, a driver may brake on the ramp or other inclined surface to adjust the deceleration to zero (0). The offset that is determined or obtained, however, may be for an accelerating vehicle. Accordingly, if the same operation of the brake pedal is used to adjust the deceleration to zero (0) after the vehicle moves to a relatively level surface, then the brakes may open or otherwise become ineffective. Since the driver may not decelerate by depressing the brake pedal while on a level road, this result may be inconsistent with the experiential frame of reference of the driver.
As further regards the implementation of a wheel deceleration control systems and/or an anti-lock brake system control system, such an implementation may be problematic since the controlled deceleration of the wheels may make it impractical for the wheel speed sensors to measure the wheel speeds when the wheel speeds are dropping relatively sharply because of relatively high wheel decelerations. In this regard, FIG. 1 shows a graph of wheel deceleration control at low friction values (xcexc), in which Vfahrzeug corresponds to a vehicle speed or velocity Vvehicle, VRad, soll corresponds to a desired wheel speed Vwheel-desired and VRad, ist corresponds to an actual wheel speed Vwheel-actual. In particular, FIG. 1 shows deceleration control at low friction values (xcexc), in which the actual wheel speed conforms to the desired wheel speed, and in which the wheel slip becomes increasingly greater until the wheel locks when a vehicle speed is not zero (0).
In certain anti-lock brake control systems, wheel locking may be detected by comparing the vehicle speed with the wheel speeds. As a practical matter, however, wheel slip and other factors may complicate the process of detecting or determining the actual vehicle speed or velocity. Accordingly, in certain anti-lock brake control systems, vehicle speed may be determined approximately based on each of the wheel speeds. Thus, for example, the output of a wheel speed sensor on each wheel may be provided to a processor for an anti-lock brake control system, in which the wheel speeds are compared to determine an estimated vehicle speed. The estimated vehicle speed may, of course, be differentiated to determine the vehicle acceleration or deceleration. If any wheel (or set of wheels) exceeds or drops below some predetermined velocity rate and/or acceleration rate, a correcting control signal may be applied to the braking system to compensate for any locking or slipping of a wheel. Accordingly, if a more accurate vehicle velocityxe2x80x94which depends on the wheel slip(s), could be determined, it is believed that a more accurate or efficient anti-lock braking control system may be provided.
The method and apparatus of some exemplary embodiments of the present invention are characterized in that a plurality of deflection displacements are determined, and then at least one wheel slip of a vehicle and at least one of a pitch angle, a road angle, and a roll angle of the vehicle are determined based on the plurality of deflection displacements. Also, at least one wheel slip of a vehicle and at least one of the pitch angle, the road angle, and the roll angle of the vehicle may be provided or otherwise made available to at least one vehicle control system.
In view of the above needs and problems, one embodiment of the present invention is directed to an apparatus for determining at least one wheel slip of a vehicle and at least one of a pitch angle, a road angle and a roll angle of the vehicle for use in at least one vehicle control system, characterized in that the apparatus includes: at least three sensing devices that are adapted for sensing a first parameter that corresponds to a longitudinal acceleration, a second parameter that corresponds to a transverse acceleration, and a third parameter that corresponds to a vertical acceleration; and a processor that determines the at least one wheel slip of the vehicle and the at least one of the pitch angle, the road angle and the roll angle based on the longitudinal acceleration, the transverse acceleration and the vertical acceleration. The at least one wheel slip of the vehicle and the at least one of the pitch angle, the road angle, and the roll angle of the vehicle may be provided to the at least one vehicle control system.
Another embodiment of the present invention is directed to a method for determining at least one wheel slip of a vehicle and at least one of a pitch angle, a road angle and a roll angle for use in at least one vehicle control system, characterized in that the method includes the steps of: determining a longitudinal acceleration; determining a transverse acceleration; determining a vertical acceleration; and determining the at least one wheel slip of the vehicle and the at least one of the pitch angle, the road angle and the roll angle based on the longitudinal acceleration, the transverse acceleration and the vertical acceleration. The at least one wheel slip of the vehicle and the at least one of the pitch angle, the road angle, and the roll angle of the vehicle may be provided to the at least one vehicle control system.
Still another embodiment of the present invention is directed to an apparatus for determining at least one wheel slip of a vehicle and at least one of a pitch angle, a road angle and a roll angle of the vehicle for use in at least one vehicle control system, including a deceleration control system, which has a braking characteristic curve, that controls a brake system based on at least one of the braking characteristic curve and an unbraked wheel acceleration, characterized in that the apparatus includes: means for sensing a first parameter that corresponds to a longitudinal acceleration, a second parameter that corresponds to a transverse acceleration, and a third parameter that corresponds to a vertical acceleration; means for determining the at least one wheel slip based on at least one of the longitudinal acceleration, the transverse acceleration and the vertical acceleration; means for determining the road angle and at least one of the pitch angle and the roll angle based on at least one of the longitudinal acceleration, the transverse acceleration and the vertical acceleration; and means for determining the unbraked wheel acceleration during a braking operation and adding the unbraked wheel acceleration as an offset to the braking characteristic curve.
Yet another embodiment of the present invention is directed to an apparatus for determining at least one wheel slip of a vehicle and at least one of a pitch angle, a road angle and a roll angle of the vehicle for use in at least one vehicle control system, characterized in that the apparatus includes: at least three deflection displacement sensing devices that are adapted for sensing a first parameter that corresponds to a first deflection displacement, a second parameter that corresponds to a second deflection displacement, and at least a third parameter that corresponds to a third deflection displacement; and a processor for determining the at least one wheel slip of the vehicle and the at least one of the pitch angle, the road angle and the roll angle based on the first deflection displacement, the second-deflection displacement, and the third deflection displacement. The at least one wheel slip of the vehicle and the at least one of the pitch angle, the road angle, and the roll angle of the vehicle may be provided to the at least one vehicle control system.
Still another embodiment of the present invention is directed to a method for determining at least one wheel slip of a vehicle and at least one of a pitch angle, a road angle and a roll angle for use in at least one vehicle control system, characterized in that the method includes the steps of: determining a first deflection displacement; determining a second deflection displacement; determining a third deflection displacement; and determining the at least one wheel slip of the vehicle and the at least one of the pitch angle, the road angle and the roll angle based on the first deflection displacement, the second deflection displacement, and the third deflection displacement. The at least one wheel slip of the vehicle and the at least one of the pitch angle, the road angle, and the roll angle of the vehicle may be provided to the at least one vehicle control system.
Yet another embodiment of the present invention is directed to an apparatus for determining at least one wheel slip of a vehicle and at least one of a pitch angle, a road angle and a roll angle of the vehicle for use in at least one vehicle control system, including a deceleration control system, which has a braking characteristic curve, that controls a brake system based on at least one of the braking characteristic curve and an unbraked wheel acceleration, characterized in that the apparatus includes: means for sensing a first parameter that corresponds to a first deflection displacement, a second parameter that corresponds to a second deflection displacement, and at least a third parameter that corresponds to at least a third deflection displacement; means for determining the at least one wheel slip based on at least one of first deflection displacement, the second deflection displacement, and the third deflection displacement; means for determining the at least one wheel slip based on at least one of first deflection displacement, the second deflection displacement, and the third deflection displacement; means for determining the road angle and at least one of the pitch angle and the roll angle based on at least one of first deflection displacement, the second deflection displacement, and the third deflection displacement; and means for determining an unbraked wheel acceleration during a braking operation and adding the unbraked wheel acceleration as an offset to the braking characteristic curve.
Further advantages of the present invention(s) are also evidenced by the claims, including the dependent claims, and the present description, including the referenced Figures.